Table 1.
Description of the cohorts of coal miners without and with coal-workers´ pneumoconiosis (CWP) and according to the severity of CWP.
| Category of CWP | Number | % | Age at Study Entry 1 (Year) | Length of Exposure (Year) | Proportion of Smokers 2 | ||
|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | % | |||
| Without CWP | 6687 | 100% | 44.0 | 6.3 | 22.9 | 5.9 | 67.3% |
| With CWP | 3476 | 100% | 49.7 | 12.39 | 20.7 | 7.80 | 66.6% |
| iCWP | 606 | 17% | 40.4 | 6.92 | 18.1 | 6.21 | 65.3% |
| sCWP | 2465 | 71% | 50.9 | 11.88 | 21.3 | 7.86 | 66.7% |
| PMF | 233 | 7% | 59.9 | 13.58 | 22.5 | 9.00 | 62.4% |
| CWP & TBC | 172 | 5% | 50.2 | 14.13 | 18.8 | 8.20 | 77.0% |
| p-value 3 | p < 0.001 | p < 0.001 | p = 0.033 | ||||
1 Age of coal miners without CWP in the year 1992 or at cessation of work in mine, age of coal miners with CWP at the time when they were compensated for the CWP; 2 smokers and ex-smokers, SD = standard deviation, iCWP = initial form of CWP, sCWP = simple CWP, PMF = progressive massive fibrosis, CWP & TBC = CWP with active tuberculosis; 3 p-value of statistical testing within the group of coal miners with CWP.